package com.lun.medium;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

import com.lun.util.BinaryTree.TreeNode;

public class BinaryTreeRightSideView {
	//方法一：DFS
    public List<Integer> rightSideView(TreeNode root) {
        List<Integer> result = new ArrayList<>();
        rightSideView(root, result, 0);
        return result;		
    }
    
    private void rightSideView(TreeNode node, List<Integer> result, int level) {
    	if(node == null) return;
    	
    	if(level == result.size())
    		result.add(node.val);
    	
    	rightSideView(node.right, result, level + 1);
    	rightSideView(node.left, result, level + 1);
    }
    
    //方法二：BFS
    public List<Integer> rightSideView2(TreeNode root) {
        List<Integer> result = new ArrayList<>();
        LinkedList<TreeNode> queue = new LinkedList<>();
        if(root == null) return result;
        queue.offer(root);
        while(!queue.isEmpty()) {
        	result.add(queue.peek().val);
        	for(int size = queue.size(); size > 0; size--) {
        		TreeNode node = queue.poll();
        	
        		if(node.right != null)
        			queue.offer(node.right);
        		
        		if(node.left != null)
        			queue.offer(node.left);
        	}
        }
        
        return result;		
    }
}
